ONCE you’ve pushed viewers to the very edge of their seats, once you’ve pushed even the president of the United States to the brink of his government-issue furniture, is it possible for a television drama to maintain anything like that level of intensity in a second season?

“Oh yes,” said Alex Gansa, one of the creators of “Homeland,” the thriller that kicks off a new season Sept. 30 on Showtime. “The show will be just as intense this year.”

His co-creator, Howard Gordon, added, “That’s the contract with the audience.”

The audience that made that pact last season immersed itself in a show widely described by critics as electrifying (in The New York Times, Alessandra Stanley said it was “almost impossible to resist”), a series followed so fervently that one special fan — President Obama — requested four copies of the finale.

In the wake of that furious ride of a first season “Homeland” was showered with recognition, including Golden Globes for best drama and for its star, Claire Danes, and nine Emmy nominations, including for best drama, best actress for Ms. Danes and best actor for her co-star, Damian Lewis. (The winners will be revealed next Sunday.) “Homeland” also scored the best audience numbers for a finale of any new Showtime series, with just over two million viewers, not far off this season’s best-ever finale figure for AMC’s “Mad Men,” 2.7 million. The “Homeland” finale viewership was topped only by an episode of “Dexter” among all shows ever on Showtime.

(When Mr. Lewis sat next to the president at a state dinner last spring, he said Mr. Obama told him, “While Michelle and the two girls go play tennis on Saturday afternoons, I go in the Oval Office, pretend I’m going to work, and then I switch on ‘Homeland.’ ”)

Ms. Danes said: “I think we were all stunned — and a little terrified by that idea. The president knows what we do?”

Chiefly, Mr. Lewis said, it was validation that the show’s seemingly far-fetched premise — a Marine held captive by Islamic terrorists is converted into a willing anti-American operative, while the C.I.A. agent on his trail suffers from mental illness — had been rendered compellingly believable. “It was Obama saying this is not unrealistic,” Mr. Lewis said.

All the accolades have put Showtime and its executives in a position they have rarely occupied: as prominent players in the pack of owners of prestige dramas that have elevated television in recent years — like AMC’s “Breaking Bad” and “Mad Men,” HBO’s “Game of Thrones” and “Boardwalk Empire,” and PBS’s “Downton Abbey.” David Nevins, Showtime’s president for entertainment, said this summer that a “Homeland” win for the best drama Emmy would “take this network to a new level.”

The attention may be gratifying, but it also has put the “Homeland” creators on the spot: How could they move the story forward and maintain its realism? The answer was not to ratchet up the tension right away but to insert some time and space.

“We had to throttle down and start in a much calmer place,” Mr. Gansa said. “If we had come back immediately after we ended, five episodes in we would have been in fantasyland.”

Season 1 established the plot: efforts by the agent, Carrie Mathison (Ms. Danes), to unravel the secret of the former Marine, Nicholas Brody (Mr. Lewis), who, she is convinced, is a threat after being turned by a terrorist leader named Abu Nazir. Season 2 finds the protagonists in new circumstances after many months. Brody is in Congress, where he can plot against America from within, though as Mr. Lewis put it:

“Brody will be come at from all sides. He would like to think he has some control over his destiny, but he’s just not going to be allowed to rest for a second.”

Carrie has experienced an even greater transition, including being ousted from the C.I.A.

“The most marked difference is that she has been outed as a mentally unstable person, and she’s taken responsibility for that,” Ms. Danes said. “A deep part of her has relaxed. She’s not so panicked about being discovered, so that’s given her a new kind of power and authority.”

In interviews this summer in Los Angeles, during a break from filming in North Carolina, the stars and creators discussed the challenges for a show carrying the highest of expectations.

“I think we were all a little spooked,” Ms. Danes said. “But as soon as we got back into making the show, all of that dissipated. You don’t have time to entertain that.” (She went back to work just as she broke the news that she is expecting her first child.)

The story now revolves around the link forged by two damaged people: Brody, brutalized by war and captivity, and Carrie, whose heroic, if obsessive, pursuit is compromised as she struggles to function with a bipolar condition. That element of her character was crucial in Ms. Danes’s decision to commit to her first television series since the well-remembered “My So-Called Life” made her a star at 15.

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The show returns for a second season with Claire Danes, right in Season 1, as a bipolar former C.I.A. agent.Credit
Ronen Akerman/Showtime

“I love her because she is so sophisticated and complex,” Ms. Danes said of Carrie. “We’re still discovering who she is together in real time.”

Ms. Danes, 33, won an Emmy for the 2010 HBO movie “Temple Grandin,” in which she played Ms. Grandin, the author and professor with autism, and she acknowledged there were parallels between that role and her current one.

“I guess I do have an interest in challenged women,” she said. “I am interested in how people work. I think if I weren’t an actor, I would be in psychology.”

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In “Homeland” Carrie battles to keep her condition secret from her superiors, including her friend Saul, played by Mandy Patinkin. But the pressure of the case and the variables of her medication eventually lead to a manic breakdown, a harrowing scene in last season’s penultimate episode. Ken Tucker, writing in Entertainment Weekly, said Ms. Danes “gave a superbly controlled performance as someone out of control.”

It was also almost all Ms. Danes. “The director said, ‘I’m just going to let it go,’ ” Ms. Danes said. “It was supposed to end much earlier than it did. That was all improvised.”

The scene left her drained. “It turns out mania is rather exhausting,” she said, but added: “It’s really kind of a wild experience to empathize on that level with someone who is that depressed. You are sort of playing with your own chemicals.”

Mr. Lewis, a British actor who can affect a flawless American accent, faced a different challenge with Brody: how to make a terrorist much more than a stock villain. Before he took the role he met with the creators and insisted that he wanted a “complex, nuanced character” — in this case a man whose acts are based on his faith, with a motivation more personal than political.

Brody is seen in flashbacks being tortured under Nazir (Navid Negahban) and then, in the fashion of a Stockholm syndrome victim, he becomes an acolyte, even growing close to Nazir’s young son. And it is the killing of that boy, in an American attack, that drives him.

Photo

The creators of “Homeland,” Howard Gordon, left, and Alex Gansa.Credit
Richard Perry/The New York Times

“They tried to establish a more personal vigilantism that Brody undergoes,” Mr. Lewis said. “Then you get into the more political argument about can nation-states commit acts of terrorism?”

“Brody is sort of the central suppurating sore infected by war,” he continued. “I don’t want to overstate the political claims of the show, but of course there’s a subliminal message there, and it’s a strong antiwar message in Brody’s character. He’s a victim of his war and his own circumstances.”

The advantage of being a cable show, he added, was that the message could be dark and not an easy case of good versus evil.

“Now, in the end, my money would be on America winning,” Mr. Lewis said. “But it’s still quite bleak that the one person who represents a hope is a broken-down, polarized person, who represents a broken, polarized America. I hope that’s not presumptuous coming from a foreigner.”

Remarkably, the creators did not map out the first season’s convoluted plot in advance. “Six episodes in, we didn’t entirely know where it was going,” Mr. Gansa said.

Mr. Gordon called it “a jazz improvisation.” The Carrie breakdown was slotted first for Episode 3, then 6, then 8. Of course, he said, in hindsight it looked inevitable that it come toward the season’s end.

He and Mr. Gansa have been through the process before, as part of the creative team behind the Fox series “24,” which also navigated through complex thriller plots without a road map. “Homeland,” which was developed from an Israeli series, “Hatufim,” was spotted by Rick Rosen, the agent who represents Mr. Gordon and Mr. Gansa, as well as Avi Nir, the top executive at Keshet, the Israeli network that commissioned the original.

“Homeland” took a major departure with its terrorist mole plot: the Israeli show concerns the effects on families when soldiers return from captivity. “We thought we could make the story in a more ‘Manchurian Candidate’ sort of way,” Mr. Gordon said.

Of course that 1962 film ends with a violent climax and its damaged American protagonist dead. “Homeland” found a way to take viewers to the brink, only to have Brody continue his campaign of sabotage and Carrie still on the hunt, even as her illness comes to the fore and she suffers a profound crisis of confidence.

“But she doesn’t realize how formidable she still is,” Ms. Danes said. “She’s confronted herself in a big, scary way, and she will reap the rewards of that.”

Correction: September 30, 2012

An article on Sept. 16 about the Showtime drama “Homeland” misspelled the given name of the actor who plays Nicholas Brody. He is Damian Lewis, not Damien. The error was repeated in an accompanying picture caption.

A version of this article appears in print on September 16, 2012, on Page AR1 of the New York edition with the headline: The Terrorist Plot Even Obama Loves. Order Reprints|Today's Paper|Subscribe